Use of pigment dyes for dispersion dyeing from aqueous media

ABSTRACT

Use of pigments according to formula (I)  
                 
 
     wherein the substituents have the meanings as defined in claim 1 for dyeing semisynthetic or synthetic hydrophobic fiber materials in aqueous media as well as semisynthetic or synthetic hydrophobic fiber materials dyed with such pigments.

[0001] The invention relates to the use of certain pigments as dispersedyestuffs in aqueous media.

[0002] The word “pigment” is of Latin origin (pigmentum) and originallydenoted a color in the sense of a coloring matter, but was laterextended to indicate colored decoration (e.g., makeup). In the lateMiddle Ages, the word was also used for all kinds of plant and vegetableextracts, especially those used for coloring. The word pigment is stillused in this sense in biological terminology; it is taken to meandyestuffs of plant or animal organisms that occur as very small grainsinside the cells or cell membranes, as deposits in tissues, or suspendedin body fluids.

[0003] The modern meaning associated with the word pigment originated inthis century. According to accepted standards (DIN 55943 and DIN 55945)the word pigment means a substance consisting of small particles that ispractically insoluble in the applied medium and is used on account ofits coloring, protective, or magnetic properties. Both pigments and dyesare included in the general term “coloring materials”, which denotes allmaterials used for their coloring properties. The characteristic thatdistinguishes pigments from soluble organic dyes is their low solubilityin solvents and binders. Pigments can be characterized by their chemicalcomposition, and by their optical or technical properties.

[0004] In the Color Index (C.I.) pigments are usually named “C.I.Pigment XY xy”. Some compounds may be named “C.I. Solvent XY xy” due totheir migration tendency in polymer application, although in water ororganic solvents these compounds may fulfill the insolubility criteriafor pigments, according to DIN 55943 and DIN 55945.

[0005] Pigments can be classified into two categories:

[0006] (i) inorganic pigments

[0007] (ii) organic pigments

[0008] The most important areas of use of pigments are paints,varnishes, plastics, artists' colors, printing inks for paper andtextiles, leather decoration, building materials (cement, renderings,concrete bricks and tiles—mostly based on iron oxide and chromium oxidepigments), leather imitates, floor coverings, rubber, paper, cosmetics,ceramic glazes, and enamels.

[0009] The paint industry uses high-quality pigments almost exclusively.An optimal, uniform particle size is important because it influencesgloss, hiding power, tinting strength, and lightening power. Paint filmsmust not be too thick, therefore pigments with good tinting strength andhiding power combined with optimum dispersing properties are needed.

[0010] White pigments are used for white coloring and covering, but alsofor reducing (lightening) colored and black pigments. They must have aminimal intrinsic color tone.

[0011] When choosing a pigment for a particular application, severalpoints normally have to be considered. The coloring properties (e.g.,color, tinting strength or lightening power, hiding power) are importantin determining application efficiency and hence economics. The followingproperties are also important:

[0012] 1) General chemical and physical properties: chemicalcomposition, moisture and salt content, content of water-soluble andacid-soluble matter, particle size, density, and hardness

[0013] 2) Stability properties: resistance toward light, weather, heat,and chemicals, anti-corrosive properties, retention of gloss

[0014] 3) Behavior in binders: interaction with the binder properties,dispersibility, special properties in certain binders, compatibility,and solidifying effect

[0015] One important field of application is the mass dyeing of polymerfibers, in particular polyester fibers. The process, wherein the polymermelt is directly dyed and spun is called “spin dyeing”. The pigment dyeis “dissolved” in the polymer melt, e.g. for polyester at temperaturesabove 260° C. For the melt spinning process the temperatures are usuallyhigher, e.g. for polyester at around 285° C. There are only few pigmentclasses which can resist these high temperatures without significantdegradation of the dye molecule.

[0016] Disperse dyes are colorants with low water solubility that, intheir disperse colloidal, form, are suitable for dyeing and printinghydrophobic fibers and fabrics.

[0017] Models for the dyeing of polyester fibers with disperse dyes havebeen developed. When the dye is applied from aqueous medium, it isadsorbed from the molecularly dispersed aqueous solution onto the fibersurface and then diffuses into the interior of the fiber. The followingparameters determine the rate of dyeing and, to some extent, theleveling properties:

[0018] (1) the dissolution rate during the transition from the dispersedcrystalline state of the dye into the molecularly dispersed phase, and

[0019] (2) the diffusion rate at the fiber surface and, especially, inthe interior of the fiber.

[0020] The rates of both processes vary with temperature.

[0021] Differences in geometry and polarity of the dye molecules canlead to wide variations in these finishing or dye-specific propertiesand can have a marked effect on the absorption characteristics of alldyes, irrespective of whether single-component or combination dyeingprocesses are used. For instance, uneven dyeing may occur when anunequal distribution of particle size results in insufficient dispersionstability and, thus, crystal growth and precipitation at the substratesurface.

[0022] As the temperature in the dyeing process is usually below 120°C., the temperature stability of the dye molecules is not of greatimportance. In some cases the temperature in the dyeing process can beup to 130-140° C. Industrially applied disperse dyes are based onnumerous chromophore systems. Approximately 60% of all products are azodyes and ca. 25% are anthraquinone dyes, with the remainder distributedamong quinophthalone, methine, naphthalimide, naphthoquinone, and nitrodyes. The dye molecules are usually modified by extensive substituentsto optimize their properties according to the product to be dyed.

[0023] Surprisingly, it was found that certain pigments used for massdyeing of polymer fibers, in particular polyester fibers (e.g. pigmentsof the trademarks Polysynthren® and Sandoplast® both Trademarks ofCLARIANT) can be used for dyeing textile fibers in aqueous media.

[0024] There is a limited range of pigments, of very different chemicalstructure, used as dispersion dyes for mass dyeing of polyester. Commonelements are that they have rather symmetrical, compact and rigidstructures with rather limited side groups, optimized in their stabilityat the high temperatures of the spin dying process.

[0025] Preferred examples for Polysynthren® and Sandoplast® pigmentswhich can be used according to the invention are listed in the ColorIndex as C.I. Solvent Red 135 and C.I. Solvent Orange 60.

[0026] The invention related to the use of pigments or mixtures ofpigments according to formula (I)

[0027] wherein R₁-R₄ independently from each other signify H, halogen,—NO₂, —CN, —OH, —CH₃, —NH₂ or NHCH₃, in a dyeing process which takesplace in aqueous media.

[0028] Preferably, pigments or mixtures of pigments are used whereinR₁-R₄ independently from each other signify H, halogen or —CN.

[0029] More preferably, pigments or mixtures of pigments are usedwherein R₁-R₄ independently from each other signify H, —Cl or —CN.

[0030] Especially preferred are pigments of formula (I) or mixtures ofpigments of formula (I) wherein all R₁-R₄ are either H or —Cl.

[0031] The pigment, wherein all R₁-R₄ of formula (I) are —Cl, is knownas C.I. Solvent Red 135 (Polysynthren® Red GFP, Trademark of CLARIANT).

[0032] The pigment, wherein all R₁-R₄ of formula (I) are H, is known asC.I. Solvent Orange 60 (Sandoplast® Orange 3G, Trademark of NOVARTIS).

[0033] According to the invention, the pigments of formula (I) are usedfor dyeing and printing semisynthetic and, preferably, synthetichydrophobic fiber materials, especially textile materials. Textilematerials consisting of blended fabrics containing such semisynthetichydrophobic fiber materials can also be dyed or printed by means of thedyes of this invention.

[0034] Suitable semisynthetic textile materials are mainly cellulose-2½acetate, cellulose tri-acetate polyamides and high molecular weightpolyesters as well as mixtures thereof with cellulose.

[0035] Synthetic hydrophobic textile materials consist mainly of lineararomatic polyester, for example of those consisting of terephthalic acidand glycols, in particular ethylene glycol or condensate of terephthalicacid and 1,4-bis(hydroxymethyl)cyclohexane; of polycarbonates, e.g.those consisting of alpha,alpha-dimethyl-4,4′-dihydroxydiphenyl-methaneand phosgene, and of fibers based on polyvinyl chloride and polyamide.

[0036] The hydrophobic synthetic materials can be in the form ofsheet-like or thread-like structures, and can be processed, for example,to yarns or woven, knitted or looped textile fabrics. The pigments offormula (I) are also suitable for dyeing hydrophobic synthetic materialin the form of micro fibers.

[0037] It is expedient to convert the pigments according to formula (I)before use, into a dye formulation. This is done by milling the dye toan average particle size of 0.1 to 10 micron. Milling can be carried outin the presence of dispersants. Typically, the dried pigment is milledwith a dispersant, and thereafter dried under vacuum or by spray drying.Printing pastes and dyebaths can be prepared by adding water to theformulation so obtained.

[0038] The pigments according to formula (I) are applied to the textilematerials by known dyeing or printing methods, e.g. those described inFrench patent application No. 1445371.

[0039] Typically, polyester fiber materials are dyed from an aqueousdispersion by the exhaust process in the presence of customary anionicor non-ionic dispersants and in the presence or absence of customaryswelling agents (carrier) in the temperature range from 65° C. to 140°C.

[0040] Cellulose-2½-acetate is preferably dyed at a temperature from 65°C. to 85° C. and Cellulose triacetate at temperatures of up to 125° C.

[0041] The pigments according to formula (I) are suitable for dyeing bythe thermosol process, for the exhaust and continuos process and forprinting as for modern imaging processes, e.g. thermo-transfer printingor ink-jet printing.

[0042] The dyeings are carried out from an aqueous liquor by the exhaustprocess, and the liquor ratio can be chosen from a wide range, forexample from 1:4 to 1:100, preferably from 1:6 to 1:50.

[0043] The dyeing time is from 20 to 90 minutes, preferably from 30 to80 minutes.

[0044] The dye liquors can additionally comprise other additives, forexample dyeing auxiliaries, dispersants, wetting agents and antifoams.

[0045] The liquor may also comprise mineral acids, such as sulfuric acidor phosphoric acid, or conveniently also organic acids, for exampleformic acid or acetic acid and/or salts, such as ammonium acetate orsodium sulfate. The acids mainly serve to adjust the pH of the dyeliquors which is preferably in the range from 4 to 5.

[0046] The pigments are usually present in the dye liquors in the formof a fine dispersion. Suitable dispersants for the preparation of thisdispersion are e.g. anionic dispersants, such as aromatic sulfonicacid/formaldehyde condensates, sulfonated creosol oil/formaldehydecondensates, lignin sulfonates or copolymers of acrylic acid derivates,preferably aromatic sulfonic acid/formaldehyde condensate or ligninsulfonated, or nonionic dispersants based on polyalkylene oxidesobtainable, for examples, by poly-addition reaction from ethylene oxideor propylene oxide. Further suitable dispersants are listed in U.S. Pat.No. 4,895,981 or U.S. Pat. No. 5,910,624.

[0047] The dyeings or printings thus obtained, have good all-roundfastness; particularly noticeable are the thermo-migration fastness,light fastness, thermo-fixation-, and pleating fastness, as well as theexcellent wet fastness.

[0048] The invention further relates to semisynthetic or, preferably,synthetic hydrophobic fiber materials, which were dyed or printed withpigments of formula (I).

[0049] In the following examples, the parts and percentages are byweight. The temperatures are given in degrees Celsius.

APPLICATION EXAMPLE

[0050] 17.5 parts of the pigment of the following formula (Ia)

[0051] with 32.5 parts of a commercial dispersing agent based on ligninsulphonates, and pulverized to a powder. 1.2 parts of this dyepreparation are added to 2000 parts of demineralized water of 70° C.,which contains 40 parts of ammonium sulfate; the pH value of the dyebath is set at 5 with 85% formic acid. 100 parts of washed polyesterfiber fabric are placed in this dye bath, the container is closed,heated to 130° C. over the course of 20 minutes, and dyeing continuesfor a further 60 minutes at this temperature. After cooling, thepolyester fiber fabric is removed from the dye bath, rinsed, soaped andcleansed by reduction with sodium hydrosulphite in the usual way. Afterthermo-fixation (180° C., 30 min), a orange dyeing is obtained with verygood all-round fastness, especially fastness to light and sublimation,in particular excellent wet fastness.

[0052] Dyeing polyester yarn can be carried out analogously with thepigment according to the following formula (Ib)

[0053] A red dyeing is obtained.

1. Use of pigments or mixtures of pigments according to formula (I)

wherein R₁-R₄ independently from each other signify H, halogen, —NO₂,—CN, —OH, —CH₃, —NH₂ or NHCH₃, for dyeing semisynthetic or synthetichydrophobic fiber materials characterized in that the dyeing processtakes place in an aqueous media.
 2. Use of a pigment according to claim1 wherein R₁-R₄ independently from each other signify H, halogen or —CN.3. Use of a pigment according to claim 1 wherein R₁-R₄ independentlyfrom each other signify H, —Cl or —CN.
 4. Use of a pigment according toclaim 1 wherein all R₁-R₄ are H.
 5. Semisynthetic or synthetichydrophobic fiber materials dyed from an aqueous liquor by the thermosolprocess, for the exhaust and continuous process and for printing inusing pigments according to anyone of claims 1-4.